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Law enforcement agencies across the United Kingdom effectively campaigned to use a face scanning system acknowledged as discriminatory against females, youths, and members of minority ethnic backgrounds, after complaining that a more accurate version produced a reduced number of investigative leads.

The Technology in Practice

UK forces use the national police database to conduct searches using historical face recognition. This process involves matching a “probe image” of a person of interest against a repository of over 19 million custody photos to identify possible hits.

Admitted Bias

The UK interior ministry admitted last week that the technology was biased. This admission followed a review by the National Physical Laboratory (NPL) determined it incorrectly matched people of Black and Asian heritage and females at much greater frequency than Caucasian males. The Home Office said it “had acted on the findings”.

“This raises the question of whether facial recognition only becomes useful if users tolerate biases in ethnicity and gender. Convenience is a poor argument for disregarding basic freedoms.”

Known Issue

Internal documents reveal that this bias has been recognized for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Senior officers were notified of the algorithmic discrimination in September 2024. The Home Office-commissioned NPL review found the system was had a higher probability to produce false positives for photos of females, individuals of Black ethnicity, and those under 40 years old.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for potential matches be raised to a point where the disparity was greatly diminished.

However, this directive was reversed the next month after forces complained that the adjusted system was producing a lower number of “useful lines of inquiry”. NPCC documents indicate the higher threshold cut the number of queries that yielded possible identifications from over half to a mere 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is currently used, the latest NPL study found the system could generate false positives for women of Black heritage nearly a hundred times more frequently than for white women at specific configurations.

The Home Office stated on these results: “The testing identified that in a specific scenarios the software is has a greater tendency to wrongly flag some population segments in its match reports.”

Balancing Utility and Fairness

Outlining the impact of the temporary raise to the system's accuracy setting, the NPCC documents state: “The change greatly lessens the impact of discrimination across legally safeguarded attributes of ethnicity, age and gender but had a substantially detrimental effect on operational effectiveness”. The papers add that police units complained that “a previously useful tool returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its plans to widen the use of biometric scanning systems. The minister for police Sarah Jones has labeled the technology as the “biggest breakthrough since genetic fingerprinting”.

Expert and Oversight Concerns

The chair of a police oversight board, head of the advisory panel for the police race action plan, said: “There was scant consideration in equality strategy sessions of the technology deployment despite obvious cross-over with the strategy's goals.

“These revelations demonstrate yet again that the pledges to combat discrimination policing has undertaken via the equality initiative are failing to be integrated into wider practice. Independent assessments have cautioned that new technologies are being rolled out in a context where racial disparities, weak scrutiny and poor data collection continue to exist.

“Any use of facial recognition must adhere to strict national standards, be subject to external review, and prove it reduces rather than compounds ethnic bias.”

Home Office Response

A government representative said: “We treat the conclusions of the study seriously and we have implemented changes. A new algorithm has been externally evaluated and acquired, which has no statistically significant bias. It will be tested early next year and will be undergo evaluation.

“Our priority is ensuring public safety. This gamechanging technology will support officers to apprehend and prosecute offenders. There is officer review in each stage of the procedure and no further action would be pursued without specialist personnel carefully reviewing the output.”